1. Field of the Invention
The present invention relates to an optical scanning device and an image forming apparatus. The present invention relates particularly to the optical scanning device equipped with a light deflector that has a rotating deflection reflective surface and to the image forming apparatus, equipped with the optical scanning device, such as a copying machine, a facsimile, a printer, or a multifunction peripheral that includes the above functions.
2. Description of the Related Art
In an image forming apparatus in which an electrophotographic process is performed, an optical scanning device has been used for image formation. In the optical scanning device, a light beam that is emitted from a light source and deflected by a light deflector is focused, for scanning, on a surface of a photosensitive element serving as an illuminated surface so as to form a latent image. For example, a laser is used as the light source, and a polygon mirror that is rotated by a motor or the like is used as the light deflector. A reflective surface provided to a side surface of a polygonal of the light deflector is illuminated with the laser light, and a scanning operation is performed with the reflected light.
Among the light beams deflected by the light deflector, a light beam that is reflected from the lens surface of the scanning optical system is a so-called unnecessary light (ghost light). If the unnecessary light is incident on the scanning optical system, a quality of an output image may deteriorate.
On the other hand, Japanese Patent No. 4154152 discloses an optical scanning device that deflects a plurality of light beams emitted from a plurality of the light sources with different deflecting surfaces of the same deflector having a plurality of deflecting surfaces. The optical scanning device focuses the plurality of light beams deflected by the different deflecting surfaces on the corresponding scanned surfaces through respective scanning lens systems that are provided for respective light beams deflected by different deflecting surfaces. The optical scanning device includes a rotating body that rotates the deflector and a claw member that prevents the rotating body from being detached. In the optical scanning device, the claw member functions as a light shielding member that shields a flare light reflected from a surface of a lens in a scanning lens system among a plurality of the scanning lens systems so that the flare light could not be incident on the other scanning lens systems among the plurality of the scanning lens systems. The claw member is provided in a non-effective area, within a main-scanning cross section, interposed between an optical path of the light beam that is incident on the deflecting surface of the deflector and an optical path of a scanning light beam that has been deflected by the deflecting surface of the deflector and is then incident on the scanned surface.
Recently, as high-density images and high-speed printing are required, a rotation speed of a rotating polygon mirror has been increased. However, if the rotating polygon mirror rotates at a high speed, a problem arises in that a wind noise increases.
For example, in the optical scanning device disclosed in Japanese Patent No. 4154152, in a case where the claw member that functions as the light shielding member is provided near the light deflector, the rotary flow of air around the light deflector is obstructed by the light shielding member, so that the noise increases.
Therefore, there has been a requirement of an optical scanning device that is capable of shielding the ghost light output from the scanning optical system with the light shielding member so as to improve a quality of formed images and reducing a directional noise associated with the rotation of the light deflector.
Therefore, there is a need for providing a light-scanning apparatus that is capable of shielding the ghost light output from the scanning optical system with the light shielding member and reducing a level of a noise caused by the light shielding member associated with the rotation of a rotating member of the light deflector.